One of the toughest accomplishments in sports is to win a championship when you're expected to win a championship. That appears to be the task facing Oklahoma.

The Sooners are the top seed in the 2013 NCAA Division I Softball Championship, one of three teams from the Big 12 Conference that will start regional play Friday. OU (47-4) has been a dominant team all season, outscoring foes by an average score of 7-1.

Coach Patty Gasso says her team has not struggled with pressure or expectations.

"The team has been very mature about the No. 1 ranking, they've been there almost the entire season," she said. "They don't talk about it much, they just conduct their business. They don't get too high, they don't get too low. They know what they're capable of. They don't press, they don't push, they don't panic."

Last season, Oklahoma reached the championship series of the Women's College World Series but Alabama won the second and third games to take home the trophy. The Sooners have made this season a redemption tour.

"This team is playing very well," Gasso said. "They're hungry and they're excited about the postseason."

Texas (44-8) is the No. 4 national seed and will host a regional this weekend. Baylor (39-14) finished third in the Big 12 and will open play in the College Station Regional.

Four teams will participate at each of 16 regional sites in a double-elimination tournament this weekend. Sixteen teams were seeded and placed at one of the regional sites. The regional winners will advance to super regional competition for a best-of-three series May 23-26 at eight campus sites.

The remaining eight teams will advance to the WCWS, an eight-team, double-elimination tournament. The championship final will be a best-of-three-series. The WCWS will be conducted May 30 through June 5 at the ASA Hall of Fame Stadium in Oklahoma City.

Oklahoma in the NCAAs: The Sooners have made the NCAA Tournament in each of coach Patty Gasso's 19 seasons as coach. Last season, Oklahoma swept through both the Regional and Super Regional to reach the Women's College World Series for the seventh time in school history. Alabama defeated OU, two games to one, to win the national title.

Oklahoma update: The Sooners became the second team in Big 12 history to sweep the top three individual awards – player of the year (Shelby Pendley), pitcher of the year (Keilani Ricketts) and coach of the year (Patty Gasso). … Oklahoma enters the NCAA tournament with a chance to become the first team since Arizona in 2001 to win a national championship with four or fewer losses. … The Sooners lead the nation in scoring and ERA. No team in the super-regional era (since 2005) has ever finished a season tops in both categories. … Sophomore Lauren Chamberlain set the Big 12 single-season record with 30 home runs last season and she hit 25 this year. That's the top two totals in Conference history.

What's next: The winner of this regional advances to the super regional against the winner of the College Station Regional. The four teams there are Texas A&M, Arizona, Baylor and Penn.

Texas in the NCAAs: Texas has participated in 14 NCAA Tournaments and nine in a row. The No. 4 national seed is the Longhorns' highest since a No. 3 bid in 2011. UT has received a top-eight seed in each of the last four years (2012/6; 2011/3; 2010/7), joining Florida as the only squads to earn a top-eight seed in each of the last four years.

Texas update: The Longhorns finished second to Oklahoma in the Big 12 Conference. The Sooners are the No. 1 seed in the NCAA tournament while the Longhorns are the No. 4 seed. Senior pitcher Blair Luna leads Division I in strikeouts per seven innings (11.9) and hits allowed per seven innings (three). Senior third baseman Taylor Hoagland ranks 18th in Division I with a .442 batting average. She leads UT in home runs with 13 and is second with 23 stolen bases. Shortstop Taylor Thom has 12 homers and leads the Longhorns in RBI with 55.

What's next: The winner of this regional advances to the super regional against the winner of the Mobile (Ala.) Regional. The four teams there are No. 13 seed South Alabama, Florida State, Mississippi Valley and Mississippi State.

Baylor in the NCAAs: The Lady Bears are making their third-straight NCAA Tournament appearance and have made the bracket eight times in the last 10 years. This will mark the second-straight season Baylor has opened with a Pac-12 school, after facing Stanford to open the 2012 Regional in Lafayette.

Baylor update: Redshirt junior Whitney Canion holds the all-time Baylor record for strikeouts with 1,149. That total is sixth on the Big 12 career list. … Third baseman Sarah Smith was named Big 12 freshman of the year and senior Kathy Shelton was named Co-Scholar Athlete of the Year … Of the 209 RBI on the year, 142 (68 percent) have come from underclassmen. Underclassmen have also accounted for 19 of the team's 27 home runs (70 percent). … If Baylor leads a game heading to the sixth inning, it has been as good as over. The Lady Bears are 30-0 when leading after five innings and 32-0 when heading to the seventh with a lead. … Baylor is 2-8 against ranked opponents this season, with both wins coming on the road (at Arizona State, at Hawaii).

What's next: The winner of this regional advances to the super regional against the winner of the Norman Regional. The four teams in that regional are No. 1 seed Oklahoma, Arkansas, Fordham and Marist.